Core barrel



April 6, 1937. Q E BURT 2,076,063

CORE BARREYL Filed Nov. ,'23,v 1955 f /9 17" .3. N/ L Tg X5@ Sar l 2O APatented Apr. 6, 1937 CORE BARREL Clarence E. Burt,

Baker Oil Tools, Inc.,

Los Angeles, Calif., assigner to Huntington Park, Calif.,

a corporation of California Application November 23, 1935, Serial No.51,281

4 Claims.

This invention relates to oil well drilling tools and particularlypeains to core barrels. i

Rotary core barrels for taking samples'or cores of formation to bepenetrated by the well bore 5 are in general use. Thesecore barrelsusually comprise an outer drill barrel fitted with a bit at its lowerend, which barrel is revolved by the drilling stem to cut or form acore. Arranged within the drill barrel is a core recovery tube whichpasses over the core as the core barrel advarices through the formation,the core remaining in this core recovery tube when the drill barrel isremoved from the bore. The drilling fluid is usually pumped downwardlythrough the drilling stem, thence between the drill barrel and the coretube to discharge at the bit. Prior core barrels have not been entirelysuccessful due to the fact that it is extremely seldom that a true coreof the entire formationpenetrated is recovered. In fact, the percentageof recovery has been small and has depended upon the character offormation being cored and the eiiiciency of the particular core barrelemployed as well as the expertness of the driller.

It is the principal object of myinvention to provide an improved rotarycore barrel capable of eiiectinga maximum recovery of a core from theformation penetrated by the core. barrel.

I accomplish this object by providing a core barrel having a drillbarrel within which a core recovery tube is suspended. I utilize thedrilling Iiiuid pumped downwardly to the bit to create a suction tendingto evacuate the core recovery tube lfrom its upper end, and therebycreating a reduced pressure area within the core tube so that thedifferential pressure between the interior pressure in the core tube andthe external pressure in the well bore will aid in projecting the coreupwardly into the core tube and thus insure aSmaximum recovery.

One form which the invention may assume is exemplied in the followingdescription and illustrated by way of example in the accompanyingdrawing, in which:

Fig. i is a central vertical section of a core barrel constructed inaccordance with my present invention.

Fig. 2 is a view in section and perspective of the water-jet pumpportion of my core barrel.

Fig. 3 is a transverse sectional view taken on line III-III of Fig. l.

Referring more particularly to the accompanying drawing, I0 indicates arotary core barrel 65 which comprises a drill barrel II fitted at itsupper end with a sub I2 by means of which it may be (Cl. Z-72) connectedwith the lower end of a drilling stem. The lower end of the drill barrelI I isfltted with the usual bit I4 for penetrating into the formationwhen the drill barrel is revolved by the drilling stem to form a coreI5.

Suspended concentrically within the drill barrel II is a core recoverytube I6, the lower end of which is fitted with the usual core trimmershoe IIwhich also is provided with a suitable type oi core catcher I8.It will be noticed that the external diameter of the core recovery tubeI6 is somewhat less than the internal diameter of the drill barrel II sothat anannular space 4occurs therebetween through which the drillingiluid may travel from the drill stem to the bit I4.

The upper end of the core recovery tube I8 is tted with a two-part coretube head I9, consisting of a lower portion 20 and an upper portion 2lwhich are threadedly connected as illustrated. The upper' end of thecore tube head I9 is conv20 nected to the sub I2 vby a suitable swivelconnection 22, which enables the drill barrel I I to revolve relative tothe core-tube I6 and its head I9. but which prevents relative axialmovement therebetween.

It is intended that 25 when the core barrel here disclosed is in'operation, that the drill barrel II revolve so that it will advance intothe formation, while the core tube I6 will advance axially with thedrill barrel 'so that it will pass over the core, but due to its swivelconnection with the drill bar-` rel, it will not revolve.

lFixed by welding or any other suitable connection within the tubularlower portion 2li loi the core tube head I9 is a strainer body 23,which" is hollow and cylindrical. At its'lower end the interior of thiskstrainer body 23 is formed with a restricted passageway 24 having avalve seat 2l at the point where it joins the interior of the body 23. Aball valve 26 is adapted to seat on this seat 25 to prevent the passageof iiuid downwardly into the upper end of the core tube. The lower endof the' strainer body 29 below the restricted passageway 24 terminatesin a strainer It will be noticed that the strainer head -23 is providedwith vertical, channels 28 extending from its upper to its lower end, sothat fluid from within the core tube I6 may pass upwardly through thestrainer 21, and thence upwardly past the' strainer head 23 through thechannels 29, which channels will occur between the interior periphery ofthe lower portion 2l! of the core tube head I9 and the strainer head 23.Likewise, iluid from the core tube may passupwardly through 55 therestricted passageway 24 by unseating ,the valve 26 into the interior ofthe strainer head 23. Radial ports 29 are formed through the sides ofthe strainer head 23 between the channels 23, which ports register withsimilar ports 30 formed through the wall of the lower portion of the.core tube head I9. Therefore, when iluid passes upwardly through therestricted passageway 24 by unseating the valve 26, it will then passinto the interior o1' the strainer head 23 and may discharge through theports 29 and 30 into the annular space between the core tube and thedrill barrel.

Arranged concentrically within the core'tube head I9 above the strainerhead 23 is a nozzle 3|, the lower end of which iits in a counterbore 32formed within the upper end of the strainer head 23. The upper end ofthe nozzle rits within Athe bore 34 oi' the upper end of the lowerportion 20 of the core tube head I9. A gland 35 is threaded into theupper extremity of the lower portion 2|l of the head I9 to secure thenozzle .3| in position.

It will be noticed that the diameter of the bore of thenozzle at itslower extremity agrees with the internal diameter of the strainer head23, while the internal diameter of the nozzle at its upper extremityagrees with the internal diameter of the/gland 35.

It will therefore be seen that due to the/fact that the upper portion 2|of the core tube head I9 is hollow, cylindrical and open-ended, thatdrilling fluid pumped downwardly through the drilling stem will passinto the upper end of the core tube head I9 and then must passdownwardly through the nozzle 3| and thence outwardly through the ports29 and 30 into the annular space between the core tube and the drillbarrel. It may pass downwardly through this annular space and dischargeat the bit in the usual manner.

I utilize the drilling iluid to create a suction in the upper end of thecore tube to partially evacuate the latter and thereby create a differiential pressure between the interior of the core tube and the exteriorthereof. This differential in pressure aids in projecting the coreupwardly into the core tube so that a maximum recovery of the core willbe edected.

It will be noticed that the nozzle 3| is in the form of a Venturi tubeso that when the drilling uid passes downwardly therethrough, itsvelocity will be increased. Small oriiices 36 are formed through .thewall of the nozzle 3| just below its restricted throat so that the iluidpassing downwardly through the nozzle will create a suction throughthese orices 39. Due to the fact that there is an annular space withinthe core tube head I9 surrounding the nozzle and communicating with theorifices 36, whichannular space communicates with the interior of thecore tube at its upper end through the channels 28, the suction createdthrough the orifices 38 will draw the uid in the core tube I8 upwardlyand discharge it through the oriilces 36 into the drilling fluid stream.In other words, there will be an evacuating action tending to evacuatethe core tube and reduce the pressure therein to a pressure under thatin the surrounding well bore. It is obvious that the differential inpressure will tend to force the core upwardly into the core tube.

What I have done in effect is to provide a water-jet pump with itssuction communicating with the interior of the cor'e tube at its upperand thence downwardly through the core tube to wash the same out beforecommencing coring operations.

After the washing action has, been complete,

the ball valve 26 is dropped downwardly throughthe drilling string whereit will iind its seat on the seat 25. The drilling string is thenrevolved and suiiicient weight is employed so that the drill barrel IIwill advance through the formation, cutting `an annulus therein andforming the core I5, which will be in alignment with the core recoverytube I6, so that it will project thereinto.

While the drilling is going on, drilling fluid under considerablepressure is continuously pumped downwardly through the drilling stringto lubricate the bit I4. This drilling iluid will pass downwardlythrough the upper portion 2| of the core tube head I9 and thence passthrough the nozzle 3| and discharge through the ports 29 and 30 to theannular space between the core tube and the drill barrel. It will, ofcourse, travel downwardly through this annular space to discharge at thebit. During the passage of the drilling fluid through the nozzle 3|, itsvelocity will be accelerated due to the Venturi shape of the nozzle 3|and will create a suction through the oriilces 3B, tending to create apartial vacuum in the space surrounding the nozzle 3| which is incommunication only with the upper end of the core tube. This-will, ofcourse, tend to evacuate the upper end of the core tube and will reducethe pressure therein to a'pressure lower than the pressure in thesurrounding well bore. The diierential in pressure will tend to forcethe core upwardly into the core tube and insure a maximum recoverythereof.

It is obvious from the `foregoing that I have provided a rotary corebarrel which is lcomparatively simple in construction and operation andwhich will be effective in obtaining a maximum core recovery of theformation penetrated.

While I have shown the preferred form of my invention, it'is to beunderstood that various changes may be made in its construction by thoseskilled in the art without departing from the spirit of the invention asdefined in the appended claims.

Having thus described my invention, what I claim and desire to secure byLetters Patent is:

1. A rotary core barrel including a drill barrel adapted to be connectedto the lower end of a drill stem in a manner where circulating iluidpumped downwardly through the drillstem will enter the upper end of thedrill barrel, a core tube mounted within the drill barrel, a centralnozzle member arranged within the drill barrel with its upper end in theline of flow of iluid from the drill stem and its lower endin'communication with the space between the drill barrel and the coretube, said nozzle having oriilces therein in communication with theinterior of the core tube whereby the ilow of iiuid through said nozzlewill create a suction through said oriilces tending to evacuate the coretube.

2. A rotary core barrel including a drillbarrclldlptedtobeconnectedtothelonrend of a drill stem, a core recoverytube suspended in said drill barrel, there being an annular spacebetween the exterior of the. corey tube and the interior of the drillbarrel, a rotary connection between the upper end of the core tube andthe drill barrel enabling fluid from the drill stem to be pumpedtherethrough into the annular space between the drill barrel and thecore tube but not into the upper end of the core tube,

a nozzle incorporated in said connection through which the uid mustpass, said nozzle having orices in communication with the interior ofthe core tube whereby the flow of fluid through the nozzle will create asuction through said orifices l5 tending to evacuate said core tube.

3'. A rotary core barrel including a drill barrel adapted to beconnected to the lower end of a drill stem, a core recovery tube mountedtherein, a swivel connection suspending said 20 core tube Within thedrill barrel, said swivel connection including a. nozzle in the form ofaVenturi tube through which uid pumped downwardly through the drill stemmust the lower end of said nozzle being in communication 25 with a spacebetween the exterior of the core bular membersuspended within saidouter` tu- 10 l bular member in a manner permitting the outer tubularmember to rotate relative thereto, the upper end of the inner tubularmember being closed to the flow of fluid pumped downwardly through thedrill stem into the upper end of the outer tubular member, anozzle inthe form of a Venturi tube Within the upper end of the outer tubularmember through which the ow of iluid from the' drill stem must pass,said nozlzle having oriiices formed therein in communication with theinner tubular member whereby a. ow of fluid through the nozzle willcreate a suction through said orifices tending to evacuate said innertubular member.

` CLARENCE E. BURT.

